Recurrent Novae at Quiescence: Systems with Giant Secondaries

Spectroscopic and photometric behaviour of the class of recurrent novae with giant secondaries (T Coronae Borealis, RS Ophiuchi, V3890 Sagittarii and V745 Scorpii) at quiescence are presented in this study. The hot component in these systems is variable, with the variability manifesting as variability in the ultraviolet luminosity, the ultraviolet and optical emission line fluxes and in the UBV/visual magnitudes. The variations are uncorrelated with the binary orbital motion. The observed ultraviolet+optical spectral characteristics of the hot component in these systems can be explained by a white dwarf+accretion disc embedded in an envelope of wind from the M giant secondary. We suggest the observed variations are a result of (a) fluctuations in the mass accretion rate; (b) changes in the column density of the absorbing, optically thick, wind envelope.Comment: 11 pages, 7 postscript figures. Uses laa.sty, eps.sty. To appear in A&A (main journal

Technical Efficiency in Maize Production in Madhya Pradesh: Estimation and Implications

The state of Madhya Pradesh is one of the traditional maize growing states, accounting for 13 per cent of the total maize area and contributing equally to the total maize production in the country. However, its productivity when compared to other maize growing states is very low. The study has found that even though a majority of the farmers cultivate improved maize cultivars, the overall technology adoption by them is poor. This may be due to the inability of a majority of farmers to follow the recommended package of practices for the improved cultivars because of the high costs involved in their adoption and lack of infrastructural facilities. Therefore, steps need to be initiated to solve this problem. A comparison of costs on cultivation of traditional, composite and hybrid cultivars has revealed that the cost increases significantly on using the improved cultivars due to higher requirements of fertilizers, irrigation, and plant protection chemicals as compared to those in the traditional varieties. However, with the significant increase in yield, the unit cost of production has been much lower in the case of improved cultivars. The economics of cultivation of maize when compared with its competing crops like paddy and soybean have revealed that the paddy is superior to all the maize cultivars in output/input ratio. The hybrid maize has been found superior to soybean as well as paddy in terms of net returns and hence the farmers could cultivate maize rather than paddy since the latter has higher water requirement. The estimation of technical efficiency of the farmers has revealed that on an average the sample farms operate 23 per cent below the frontier output levels. Hence, it has been observed that the maize output can be increased through adoption of proper technology by the farmers. It requires support from both the state government (in terms of providing infrastructural/ institutional support like drying and storage facilities, arrangement for assured procurement, etc.) as well as the private companies (in terms of supply of quality seeds and chemical pesticides at reasonable prices).Agricultural and Food Policy,

Evolving clinical profile of IL-1β, IL-10 and CTLA-4 gene in rheumatoid factor positive Caucasian population

Rheumatoid arthritis (RA), a systemic autoimmune condition, causes joint damage and sometimes extra-articular lesions (cutaneous vasculitis, neuropathy, Felty’s syndrome, pericarditis, intersticial lung disease) that may be life threatening. The reason why extra-articular features will develop in rare RA patients is unknown. Our study was aimed to find any disease correlation with respect to a few genetic loci implicated in rheumatoid arthritis. In our study no significant association was observed for Il-1β and IL-10. However CTLA-4 showed polymorphism in RA and controls. In our earlier article we reported polymorphism of HLA-DRB1 in Caucasian population. The study was conducted on 60 patients, where 30 were control and 30 were diseased. All the patients selected for the study were Rf (rheumatoid factor) positive. Therefore the studies need to be conducted on larger group of patients, so that the association can be verified in Caucasian population (Indian scenario)

GMRT Observations of the 2006 outburst of the Nova RS Ophiuchi: First detection of emission at radio frequencies < 1.4 GHz

The first low radio frequency (<1.4 GHz) detection of the outburst of the recurrent nova RS Ophiuchi is presented in this letter. Radio emission was detected at 0.61 GHz on day 20 with a flux density of ~48 mJy and at 0.325 GHz on day 38 with a flux density of ~ 44 mJy. This is in contrast with the 1985 outburst when it was not detected at 0.327 GHz even on day 66. The emission at low radio frequencies is clearly non-thermal and is well-explained by a synchrotron spectrum of index alpha ~ -0.8 (S propto nu^alpha) suffering foreground absorption due to the pre-existing, ionized, warm, clumpy red giant wind. The absence of low frequency radio emission in 1985 and the earlier turn-on of the radio flux in the current outburst are interpreted as being due to higher foreground absorption in 1985 compared to that in 2006, suggesting that the overlying wind densities in 2006 are only ~30% of those in 1985.Comment: 14 pages, 1 figure. Accepted for publication in ApJ

Heavy Quarks Above the Top at the Tevatron

Recent developments in models with warped extra dimensions have opened new possibilities for vector-like quark studies at hadron colliders. These new vector-like quarks can mix sizably with light Standard Model quarks without violating low energy constraints. We perform a model-independent analysis to determine the Tevatron reach in the search for new quarks. We find that the Tevatron has great potential to observe such quarks via their electroweak single production due to their mixing with valence quarks. With 4 (8) fb-1 integrated luminosity, one may reach a 5\sigma statistical significance for a heavy quark of mass 580 (630) GeV if the heavy quark-Standard Model quark mixing parameter is order one.Comment: Version published in Phys. Rev. D; 19 pages, 4 figures; extended version including model building example; added Table

Anonymity for practical quantum networks

Quantum communication networks have the potential to revolutionise information and communication technologies. Here we are interested in a fundamental property and formidable challenge for any communication network, that of guaranteeing the anonymity of a sender and a receiver when a message is transmitted through the network, even in the presence of malicious parties. We provide the first practical protocol for anonymous communication in realistic quantum networks.Comment: 5 pages, published versio

Novae as a Mechanism for Producing Cavities around the Progenitors of SN 2002ic and Other SNe Ia

We propose that a nova shell ejected from a recurrent nova progenitor system created the evacuated region around the explosion center of SN 2002ic. In this picture, periodic shell ejections due to nova explosions on a white dwarf sweep up the slow wind from the binary companion, creating density variations and instabilities that lead to structure in the circumstellar medium (CSM). Our model naturally explains the observed gap between the supernova explosion center and the CSM in SN 2002ic, accounts for the density variations observed in the CSM, and resolves the coincidence problem of the timing of the explosion of SN 2002ic with respect to the apparent cessation of mass-loss in the progenitor system. We also consider such nova outburst sweeping as a generic feature of Type Ia supernovae with recurrent nova progenitors.Comment: Accepted to ApJL. 11 pages, 1 tabl

Evolving clinical profile of HLA-DRB1, MMP1 and NF-Κb gene in rheumatoid factor positive Caucasian population

Rheumatoid arthritis (RA), a systemic autoimmune condition, causes joint damage and sometimes extra-articular lesions (cutaneous vasculitis, neuropathy, Felty’s syndrome, pericarditis, intersticial lung disease) that may be life threatening. The reason why extra-articular features will develop in rare RA patients is unknown. Our study was aimed to find any disease correlation with respect to a few genetic loci implicated in rheumatoid arthritis. In our study no significant association was observed for NFkB1 and MMP-1. However HLA-DRB1 showed polymorphism in RA and controls. The study was conducted on 60 patients, where 30 were control and 30 were diseased. All the patients selected for the study were RF (rheumatoid factor) positive. Therefore the studies need to be conducted on larger group of patients, so that the association can be verified in Caucasian population (Indian scenario)